<!doctype html>
<html lang="en">	
	<head>
		<meta charset="UTF-8">
		<meta name="Generator" content="EditPlus®">
		<meta name="Author" content="">
		<meta name="Keywords" content="">
		<meta name="Description" content="">
		<title>图片案例练习</title>
		<style>
			*{margin:0;padding:0;}
			a{text-decoration:none;}
			ul,li{list-style:none;}
			body{font-size:12px;font-family:"微软雅黑";}
			.box{
				width:400px;
				height:400px;
				background:#ccc;
				margin:50px auto;
			}
			.line{
				position:relative;
				width:100%;
				height:100%;
				background:rgba(0,0,0,.5);
			}
			.line:after,line:before{
				position:absolute;
				background:red;
				content:"";
			}
			.line:after{
				top:0;
				left:-100%;
				width:100%;
				height:10px;
			}
			.line:before{
				height:100%;
				width:10px;
				background:red;
			}
		</style>
	</head>
	<body>
		
		<div class="box">
			<div class="line"></div>
		</div>
			
		
		
	</body>
</html>
